97 lines
3.8 KiB
C
97 lines
3.8 KiB
C
/*
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* Copyright (c) 2013, Institute for Pervasive Computing, ETH Zurich
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*/
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/**
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* \file
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* Example resource
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* \author
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* Matthias Kovatsch <kovatsch@inf.ethz.ch>
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*/
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#include <string.h>
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#include "rest-engine.h"
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static void res_get_handler(void *request, void *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset);
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/*
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* For data larger than REST_MAX_CHUNK_SIZE (e.g., when stored in flash) resources must be aware of the buffer limitation
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* and split their responses by themselves. To transfer the complete resource through a TCP stream or CoAP's blockwise transfer,
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* the byte offset where to continue is provided to the handler as int32_t pointer.
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* These chunk-wise resources must set the offset value to its new position or -1 of the end is reached.
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* (The offset for CoAP's blockwise transfer can go up to 2'147'481'600 = ~2047 M for block size 2048 (reduced to 1024 in observe-03.)
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*/
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RESOURCE(res_chunks,
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"title=\"Blockwise demo\";rt=\"Data\"",
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res_get_handler,
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NULL,
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NULL,
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NULL);
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#define CHUNKS_TOTAL 2050
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static void
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res_get_handler(void *request, void *response, uint8_t *buffer, uint16_t preferred_size, int32_t *offset)
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{
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int32_t strpos = 0;
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/* Check the offset for boundaries of the resource data. */
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if(*offset >= CHUNKS_TOTAL) {
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REST.set_response_status(response, REST.status.BAD_OPTION);
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/* A block error message should not exceed the minimum block size (16). */
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const char *error_msg = "BlockOutOfScope";
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REST.set_response_payload(response, error_msg, strlen(error_msg));
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return;
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}
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/* Generate data until reaching CHUNKS_TOTAL. */
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while(strpos < preferred_size) {
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strpos += snprintf((char *)buffer + strpos, preferred_size - strpos + 1, "|%ld|", *offset);
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}
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/* snprintf() does not adjust return value if truncated by size. */
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if(strpos > preferred_size) {
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strpos = preferred_size;
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/* Truncate if above CHUNKS_TOTAL bytes. */
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}
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if(*offset + (int32_t)strpos > CHUNKS_TOTAL) {
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strpos = CHUNKS_TOTAL - *offset;
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}
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REST.set_response_payload(response, buffer, strpos);
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/* IMPORTANT for chunk-wise resources: Signal chunk awareness to REST engine. */
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*offset += strpos;
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/* Signal end of resource representation. */
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if(*offset >= CHUNKS_TOTAL) {
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*offset = -1;
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}
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}
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